The invention relates to a turbine flowmeter for fluids of the type comprising a casing having a chamber of substantially circular section into which there open an admission orifice, substantially tangential to the said chamber, and an outlet orifice, a turbine or rotor equipped with blades pivoting in the said chamber about the axis of the said chamber under the action of the fluid passing through the chamber from the admission orifice to the outlet orifice, means for measuring the speed of rotation of the rotor, the wall of the said chamber adjacent to the extremities of the turbine blades being provided with recesses substantially parallel to the axis of the chamber and creating a turbulence in the flow of fluid through the chamber.